1. Field of the Invention
The present disclosure relates to an observation optical system which combines as an overall image a plurality of original images formed on image forming elements such as a liquid crystal display device (i.e., a liquid crystal panel), and enlarges and presents the overall image to an observer. In particular, an embodiment of the present invention relates to an observation optical system suitable for a head-mounted display (HMD).
2. Description of the Related Art
There is a demand with respect to the HMD for achieving a wide angle-of-view to increase realistic and dynamic sensation. On the other hand, it is desirable for the HMD to be small, and in particular, to be thin, in view of a balanced weight of the device. U.S. Pat. No. 7,864,459 discusses a thin-type observation optical system.
More specifically, U.S. Pat. No. 7,864,459 discusses separating two optical elements which configure the optical system, from each other. However, further improvements are required in thinning of the observation optical system and manufacturability including reducing time necessary for performing assembling adjustment.